To me, it feels like the plastic is bending during the pull. It doesn't really 'break'... The hammer just eventually scrapes off the sear, and then finally boom. It's my only polymer gun, and I think that's part of it too.

All that said, I haven't replaced it, because as you say, it goes bang. Also hard to spend half the gun's price on a trigger upgrade because I'm being a little bitch.